org.slf4j.helpers.MessageFormatter Maven / Gradle / Ivy
/*
* Copyright (c) 2004-2007 QOS.ch
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package org.slf4j.helpers;
/**
* Formats messages according to very simple substitution rules. Substitutions
* can be made 1, 2 or more arguments.
*
* For example,
*
MessageFormatter.format("Hi {}.", "there");
* will return the string "Hi there.".
*
* The {} pair is called the formatting anchor. It serves to
* designate the location where arguments need to be substituted within the
* message pattern.
*
* In the rare case where you need to place the '{' or '}' in the message
* pattern itself but do not want them to be interpreted as a formatting
* anchors, you can espace the '{' character with '\', that is the backslash
* character. Only the '{' character should be escaped. There is no need to
* escape the '}' character. For example,
*
MessageFormatter.format("Set \\{1,2,3} is not equal to {}.", "1,2");
* will return the string "Set {1,2,3} is not equal to 1,2.".
*
*
* The escaping behaviour just described can be overridden by
* escaping the escape character '\'. Calling
*
MessageFormatter.format("File name is C:\\\\{}.", "file.zip");
* will return the string "File name is C:\file.zip".
*
*
* See {@link #format(String, Object)}, {@link #format(String, Object, Object)}
* and {@link #arrayFormat(String, Object[])} methods for more details.
*
* @author Ceki Gülcü
*/
public class MessageFormatter {
static final char DELIM_START = '{';
static final char DELIM_STOP = '}';
/**
* Performs single argument substitution for the 'messagePattern' passed as
* parameter.
*
* For example,
*
*
* MessageFormatter.format("Hi {}.", "there");
*
*
* will return the string "Hi there.".
*
*
* @param messagePattern
* The message pattern which will be parsed and formatted
* @param argument
* The argument to be substituted in place of the formatting anchor
* @return The formatted message
*/
public static String format(String messagePattern, Object arg) {
return arrayFormat(messagePattern, new Object[] { arg });
}
/**
*
* Performs a two argument substitution for the 'messagePattern' passed as
* parameter.
*
* For example,
*
*
* MessageFormatter.format("Hi {}. My name is {}.", "Alice", "Bob");
*
*
* will return the string "Hi Alice. My name is Bob.".
*
* @param messagePattern
* The message pattern which will be parsed and formatted
* @param arg1
* The argument to be substituted in place of the first formatting
* anchor
* @param arg2
* The argument to be substituted in place of the second formatting
* anchor
* @return The formatted message
*/
public static String format(String messagePattern, Object arg1, Object arg2) {
return arrayFormat(messagePattern, new Object[] { arg1, arg2 });
}
/**
* Same principle as the {@link #format(String, Object)} and
* {@link #format(String, Object, Object)} methods except that any number of
* arguments can be passed in an array.
*
* @param messagePattern
* The message pattern which will be parsed and formatted
* @param argArray
* An array of arguments to be substituted in place of formatting
* anchors
* @return The formatted message
*/
public static String arrayFormat(String messagePattern, Object[] argArray) {
if (messagePattern == null) {
return null;
}
int i = 0;
int len = messagePattern.length();
int j = messagePattern.indexOf(DELIM_START);
StringBuffer sbuf = new StringBuffer(messagePattern.length() + 50);
for (int L = 0; L < argArray.length; L++) {
j = messagePattern.indexOf(DELIM_START, i);
if (j == -1 || (j + 1 == len)) {
// no more variables
if (i == 0) { // this is a simple string
return messagePattern;
} else { // add the tail string which contains no variables and return
// the result.
sbuf.append(messagePattern.substring(i, messagePattern.length()));
return sbuf.toString();
}
} else {
char delimStop = messagePattern.charAt(j + 1);
if (isEscapedDelimeter(messagePattern, j)) {
if(!isDoubleEscaped(messagePattern, j)) {
L--; // DELIM_START was escaped, thus should not be incremented
sbuf.append(messagePattern.substring(i, j - 1));
sbuf.append(DELIM_START);
i = j + 1;
} else {
// The escape character preceding the delemiter start is
// itself escaped: "abc x:\\{}"
// we have to consume one backward slash
sbuf.append(messagePattern.substring(i, j-1));
sbuf.append(argArray[L]);
i = j + 2;
}
} else if ((delimStop != DELIM_STOP)) {
// invalid DELIM_START/DELIM_STOP pair
sbuf.append(messagePattern.substring(i, messagePattern.length()));
return sbuf.toString();
} else {
// normal case
sbuf.append(messagePattern.substring(i, j));
sbuf.append(argArray[L]);
i = j + 2;
}
}
}
// append the characters following the second {} pair.
sbuf.append(messagePattern.substring(i, messagePattern.length()));
return sbuf.toString();
}
static boolean isEscapedDelimeter(String messagePattern,
int delimeterStartIndex) {
if (delimeterStartIndex == 0) {
return false;
}
char potentialEscape = messagePattern.charAt(delimeterStartIndex - 1);
if (potentialEscape == '\\') {
return true;
} else {
return false;
}
}
static boolean isDoubleEscaped(String messagePattern, int delimeterStartIndex) {
if (delimeterStartIndex >= 2
&& messagePattern.charAt(delimeterStartIndex - 2) == '\\') {
return true;
} else {
return false;
}
}
}